Natural History of Limbs with Arterial Insufficiency and Non-Healing Ulcerations Treated Without Revascularization

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William Marston, MD, Stephen W. Davies, BS, William Cade, MPH, Joseph Fulton, MD, Robert Mendes, MD, Mark Farber, MD, Blair Keagy, MD.
University of North Carolina, Chapel Hill, NC, USA.

BACKGROUND:
Recently, drug therapies and interventions targeting patients with critical limb ischemia have been introduced. However, the natural history of limbs affected by ischemic ulceration is poorly understood. In this report, we describe the outcome of limbs with leg ulcers and arterial insufficiency (AI) treated with wound healing techniques who were not candidates for revascularization.
METHODS:
A prospectively maintained database of limb ulcers treated at a comprehensive wound center was queried retrospectively to identify patients with arterial insufficiency defined as an ankle brachial index (ABI) < 0.7 or a toe pressure < 50. Patients were treated without revascularization when medical comorbidity or anatomic considerations did not allow intervention with acceptable risk. Ulcers were treated with a protocol emphasizing pressure relief, debridement, infection control, moist wound healing, and occasional use of platelet derived growth factor (PDGF) or bioengineered human skin equivalents (BSE). Patients were seen at 1 to 3 week intervals for treatment and documentation of wound status and variables. All patients were followed for a minimum of 6 months or until complete healing or limb amputation occurred. Risk factors analyzed for their impact on healing and amputation risk included age, gender, diabetes, chronic renal insufficiency (Cr > 2.5), severity of ischemia measured by ABI or toe pressure, wound grade, wound size, and wound location.
RESULTS:
Between January 1999 and March 2005, 142 patients with 169 limbs having AI and full thickness ulceration were treated without revascularization. Mean patient age was 70.8+14.5. Diabetes and CRI was present in 70.4% and 27.8% of patients respectively. Toe amputations or other foot sparing procedures were performed in 28% of limbs. Overall, below or above knee amputation was required in 37 limbs. By life table analysis, 16% of limbs required amputation within 6 months of initial treatment, 22% at 12 months, and 23% at 18 months. Complete wound closure was achieved in 25% by 6 months, 52% by 12 months, and 62% by 18 months. Statistical analysis showed a correlation between ABI and the risk of limb loss. In limbs with an ABI < 0.5, 24% and 29% of limbs required amputation at 6 and 12 months respectively compared to 8% and 10% of limbs in patients with an ABI > 0.5 (p<0.01). In addition, the primary factor associated with wound healing was initial wound size. Wounds less than 5.0cm² healed more rapidly than those greater than 5.0cm² (p<0.005).
CONCLUSIONS:
In the majority of cases, limb salvage can be achieved in patients with AI and chronic non-healing limb ulcers with a conservative program of wound management without revascularization. However, healing proceeds slowly, requiring more than a year in many cases. Patients with an ABI below 0.5 are less likely to experience limb salvage. Interventions designed to improve outcomes in CLI should stratify outcomes based on ABI and must include a comparative control group given the natural history of ischemic ulcers treated in a dedicated wound program.

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